This PDF file contains the front matter associated with SPIE Proceedings Volume 7235, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.

Developments in fiber optic communications have been rejuvenated after the glut of the overcapacity at the turn of the century. The boom of video-centric network applications finally resulted in another wave of vast build-outs of broadband access networks such as FTTH, DOCSIS 3.0 and WI-FI systems, which in turn also drove up the bandwidth demands in metro and regional WDM networks. These new developments have rekindled research interests on technologies not only to meet the surging demand, but also to upgrade legacy network infrastructures in an evolutionary manner without disrupting existing services and incurring significant capital penalties. Standard bodies such as IEEE, ITU and OIF have formed task forces to ratify 100Gb/s interface standards. Thanks to the seemingly unlimited bandwidth in single-mode fibers, advances in optical networks has traditionally been fueled by more capable physical components such as more powerful laser, cleaner and wider bandwidth optical amplifier, faster modulator and photo-detectors, etc. In the meanwhile, the mainstream modulation technique for fiber optic communication systems has remained the most rudimentary form of on-off keying (OOK) and direct power detection for a very long period of time because spectral efficiency had never been a concern. This scenario, however, is no longer valid as demand for bandwidth is pushing the limit of current of current WDM technologies. In terms of spectral use, all the 100-GHz ITU grids in the C-band have been populated with 10Gb/s wavelengths in most of the WDM transport networks, and we are exhausting the power and bandwidth offered on existing fiber plant EDFAs. Beyond 10Gb/s, increasing the transmission to 40Gb/s by brute force OOK approach incurs significant penalties due to chromatic and polarization mode dispersion. With conventional modulation schemes, transmission impairments at 40Gb/s speed and above already become such difficult challenges that the efforts to manage these problem have severely hindered the rate of return on the investment from an economical viewpoint, let alone 100Gb/s transmission. In addition, to enable fast turn-up of new services and reduce network operation costs, carriers are also deploying reconfigurable optical add/drop multiplexers (ROADMs) and transparent optical networks. ROADMs impose more impairments to transmitted signals and are important considerations in designing backbone transmission links. Recently, advanced modulation schemes have been investigated in both the academia and industry as ways to improve the spectral efficiency and alleviate transmission impairments. Signal processing techniques familiar to traditional telecommunication engineers are also playing more and more important roles in optical communications because of the fast advance in mixed signal processing and growing abundance of computational power. In this invited talk, we review the current challenges faced in upgrading existing 10Gb/s metro and regional WDM networks and the potential solutions to enable 40 and 100Gb/s wavelength services.

FTTH or FTTC, depending on countries and areas, will be the key technology for operators to differentiate themselves from competitors and win market share. Such a disruptive evolution of the access network should be supported by a significant re-design of the higher network layers. In the present paper, the required features of these new WDM networks are presented. Capacity and cost are the two obvious drivers. But versatility will be crucial to cope with an uncertain context (tedious prediction of traffic, regulation and services) and with very diverse population densities. Finally we also address how PON could benefit from mature WDM technologies to ease the global network design.

This invited talk will review the development of ultrafast all-optical LAN technologies, conducted by New Energy and Industrial Technology Development Organization (NEDO), Japan. First, we will provide an outlook for the energy issues of future network equipment, then point out the importance of optical circuit-switched networks, particularly for the future local area networks in the forthcoming ultra-high definition, or 'Super Hi-vision', video era. To realize ultrafast all-optical LAN, we argue that scalable network interface card technologies are the key. As specific development topics, 40G-CMOS based optical transceivers, picosecond all-optical switching using the inter-subband transition (ISBT) devices, high-operating-temperature semiconductor optical amplifiers (SOA), and integrated wide-dynamic-range wavelength converters will be introduced.

In this paper, we review recent developments in coherent, spectral phase encoded optical code-division multiplexed (OCDM) systems employing integrated micro-ring resonator coding technologies and consider its application to data confidentiality in optical networks. In addition, we discuss how such systems can be designed to be compatible with conventional dense wavelength-division multiplexing (DWDM) networking, and review our experimental progress in advanced modulation formats for improved spectral efficiency (up to 0.87 b/s/Hz) as well as the capability for long transmission distances (up to 400 km).

Reconfigurable Optical Add-Drop Multiplexers (ROADMs) are the key nodal sub-systems that are used to implement modern DWDM networks. They provide network flexibility by switching wavelengths among fibers under software control without expensive conversion to the electronic domain. They speed up provisioning time, reduce operational costs and eliminate human errors. Two general types of ROADMs are used in Metro optical networks, two-degree and multi-degree, where the degree refers to the numbers of DWDM fibers entering and exiting the ROADM node. A twodegree ROADM is like a location on a highway with off and on ramps to drop off and accept local traffic while a multidegree ROADM is like an interchange where highways meet and is used for interconnecting DWDM rings or for mesh networking. The paper describes two-degree and multi-degree ROADM architectures and how these relate to the technology alternatives used to implement the ROADMs themselves. Focus is provided on the role and expected evolution of the wavelength selective switch (WSS) which is the primary engine used to power ROADMs.

In this paper, design of an all-optical switch using MZI switching elements with SOA's and its works performance is explained. The effect of variations of output power with respect to control signal wavelength, data signal power and control signal power are examined and plotted. Also the optical spectrum and time domain analysis has been done to demonstrate its operational features.

The metro optical network growth continues so far unabated by the slowing economy. Main drivers for this are enterprise connectivity, triple play and high-bandwidth hungry internet applications. Every day more and more of the population is connected with a projection to have five (5) billion people connected by 2010 and an overall traffic increase of one-hundred fold by 2015. While key applications drive these deployments, it is the decrease in network cost that is the bandwidth enabler. Stagnant average revenue per user (ARPU) makes further reduction in the total cost of ownership key. As costs progress due to volume and technology maturity, prices drop and a stronger demand for bandwidth is generated in the market. Today the 10G Ethernet LAN PHY services drive this growth and the cost for 10G hardware continues to improve further enabling profitable growth. While 10G is the key transport technology today, there is a push to bring higher line rates into the metro deployments. 40G is currently undergoing a mass adoption in the long-haul core networks. The volumes in long-haul network deployments are driving down the costs making it a viable evolution path for the metro networks over time.

Due to the doubling of the internet traffic every twelve month and upgrading existing optical metro-, regio- and long haul transport networks, the migration from existing networks toward high speed optical networks with channel data rates up to 100 Gbit/s/λ is one of the most important questions today and in the near future. Current WDM Systems in photonic networks are commonly operated at linerates of 2.5 and 10 Gbit/s/λ and major carriers already started the deployment of 40 Gbit/s/λ services. Due to the inherent increase of the bandwidth per channel, limitations due to linear and non-linear transmission impairments become stronger resulting in a highly increased complexity of link engineering, potentially increasing the operational expenditures (OPEX). Researchers, system vendors and -operators focus on investigations, targeting the relaxation of constraints for 100 Gbit/s transmission to find the most efficient upgrade strategies. The approaches towards increased robustness against signal distortions are the transmission of the 100 Gbit/s data signals via multiple fibers, wavelength, subcarriers or the introduction of more advanced modulation formats. Different modulation schemes and reduced baud rates show strongly different optical WDM transmission characteristics. The choice of the appropriate format does not only depend on the technical requirements, but also on economical considerations as an increased transmitter- and receiver-complexity will drive the transponder price. This article presents investigations on different approaches for the upgrade of existing metro-/ regio and long haul transport networks. The robustness against the main degrading physical effects and economy of scale are considered for different mitigation strategies.

To open up new optical frequency resources for communications, a concept called all-band photonics is proposed. This concept focuses on 1-μm waveband photonic transmission and device technologies, thereby pioneering a new waveband for photonic transport systems (PTSs). To construct the 1-μm PTS, a novel semiconductor light-source, optical-fiber transmission lines, and optical amplifiers are developed. In this paper, we demonstrate a 1-μm waveband, high bit-rate (>10 Gbps), and long-distance photonic transmission system by using attractive photonic devices such as mode-locked semiconductor lasers (MLL), wavelength tunable quantum dot (QD) lasers, QD optical frequency comb lasers (QD-CMLs), holey-fiber transmission lines, and Ytterbium-doped fiber amplifiers (YDFAs).

The world wide growing bandwidth demand in optical networks leads to channel data rates of 40 Gbit/s and higher (e.g. 100 Gbit/s). At these data rates polarization mode dispersion (PMD) is one of the limiting factors even in metro networks. Due to stochastically changing environmental conditions, such as temperature drifts, vibrations and pressure, PMD parameters fluctuate with time. Therefore, adaptive compensation and fast measurement systems are required to overcome the PMD induced impairments. One possibility for the realization of a fast measurement system is the spectrally resolved measurement of the Stokes parameters of modulated optical signals. This offers the advantage to directly measure first and second order PMD in the channel during operation of the optical transmission system at various locations in the network. Additionally the optical signal to noise ratio (OSNR) can be determined. The obtained information can be used to steer polarization mode dispersion compensation modules (PMDCs), for long term measurements at different points in the network studying the statistical behavior of PMD in real networks and for network management purposes e.g. routing information. In this paper measurement results for two realized polarimeter setups, a coherent detection polarimeter and a stimulated Brillouin scattering based one, in a 10 Gbit/s NRZ system, are shown.

One of the major impairments in high-speed optical transmission links is Polarization-Mode Dispersion (PMD). We propose the method of electronic predistortion (EPD) for the mitigation of PMD. This approach has already been successfully applied for the compensation of Chromatic Dispersion (CD) and Fiber-Nonlinearities. The advantage of this method is that impairments can efficiently be mitigated without the need for coherent reception. The proposed scheme is based on the possibility to control the optical field at the transmitter by using two complex modulators for the modulation of two orthogonally polarized optical signals. If the physical origin of PMD is exactly known then the ideal predistorted field and the corresponding electrical driving signals can be computed accurately. In practice, however, this information is not available. Therefore it is shown how to determine appropriate driving signals for a set of measured PMD parameters. Measurements will be communicated through a feedback channel in practice. We suggest a possible strategy for application of this technique in scenarios, in which the adaptation speed is intrinsically limited due to the round-trip delay. Numerical simulations reveal that the use of EPD can significantly increase the tolerance towards PMD in comparison to a system without compensation.